1. Field of the Invention
This invention relates to a window blind, more particularly to an operating device for rotating a winding roller of a window blind to wind up a window covering.
2. Description of the Related Art
A conventional window blind generally includes a winding roller, a window covering extending downwardly from the roller, and a ring chain (or cord) disposed on an end portion of the roller and extending downwardly. A user can pull the ring chain to rotate the winding roller such that the window covering can be raised or lowered. However, such ring chain poses choking or strangulation hazards to young children. Another window blind such as those disclosed in EP Application No. 10157918.3 and U.S. patent application Ser. No. 12/696,173, is provided with an operating rod to replace the ring chain. The operating rod extends vertically and has an upper end coupled with a winding roller by a rotation transmitting mechanism such that vertical rotation of the operating rod results in horizontal rotation of the winding roller, and a lower end coupled with a hinged handle which can be manipulated to rotate the operating rod. Since the hinged handle is disposed remote from the winding roller, it is hard for a force applied to the hinged handle to be transmitted to the rotation transmitting mechanism, thereby rendering operation of the operating rod laborious and inefficient.
In a co-pending U.S. patent application Ser. No. 13/036,066, entitled “Operating Device for Rotating a Winding Roller of a Window Blind,” filed by the applicant, there is disclosed an upright rotating shaft which is operated to rotate by means of engagement between a sleeve shell and one of upper and lower coupling members.
It is desirable to improve the aforesaid operating device to simplify the structure thereof.